Controlling the growth of pathogenic bacteria is one of the biggest issues in the field of biological chemistry. Two representative pathogenic bacteria in plants and animals are Agrobacterium tumefaciens(A. tumefaciens) and Pseudomonas aeruginosa(P. aeruginosa). A. tumefaciens is known to be the cause of Crown Gall disease. Crown gall, a disease of roots and stems, occurs in over 140 species of dicotyledon. P. aeruginosa makes biofilms. A biofilm is a slimy layer composed of microorganisms attached to a surface by extracellular polymeric substances (EPS) secreted by the cells during metabolism. P. aeruginosa in biofilms has the capability to protect themselves from attacks by other agents such as antibiotics.
Understanding quorum sensing (QS) mechanism is important to solve the problems such as diseases and biofilm formation which get accomplished by bacterial QS. Bacteria communicate with each other by a mechanism known as QS. QS is a term to describe the phenomenon that a single cell senses the cell density. Bacteria release signaling molecules or autoinducers (AI) out of the cell. Once bacteria reach a high cell density, a high concentration of AI accumulates in the surrounding medium. AI docks with a receptor protein in a cell and AI-receptor protein complex regulates various gene expressions concerning the production of virulence factors, biofilms and infection of plant or animal, depending on a cell density.
Therefore, it is necessary to develop the antagonizing agents that can interfere with the normal QS regulation for controlling the undesired bacterial activities, such as virulence factor production by pathogenic bacteria or biofilm formation by environmental microorganisms.
Moreover, the development of new antagonist blocking QS regulation of various bacteria is demanded.